Why do the villagers suspect that Alys is involved in dark magic in the novel, Dragon’s Bait?

It is unusual for a girl to learn her father's trade; the man is supposed to take on male apprentices if he has no sons of his own to carry on his work. The author alludes that this is why the villagers of St. Toby's so readily believe that Alys is somehow fey, being associated with dark magic. She had let herself dream of actually becoming a tinsmith.